The invention relates, in general, to a ring channel blower, also known as a side channel or lateral duct blower, that is intended, in particular, for combustion air conveyance in heaters, such as motor vehicle heaters. More specifically, the invention relates to a ring channel blower of the type wherein an impeller edged with vanes rotates opposite a ring channel that is formed in a housing part of the ring channel blower with an inlet opening, a discharge opening, and a cross piece-shaped interrupter lying between them, as well as, in some cases, a bypass channel which can be adjusted by a setscrew for output regulation.
In U.S. Pat. No. 4,439,095, a ring channel blower is described, wherein output regulation is achieved by a bypass channel, that is formed in a partition wall provided between the inlet opening and discharge opening of the channel, the cross section of which can be adjusted by a screwing in or out of a setscrew.
From German Offenlegungsschrift No. 25 31 740 and German Gebrauchsmuster No. 66 04 782, ring channel blowers of the type mentioned above are known in which a section of the cross piece-shaped interrupter extends upstream from the discharge opening and covers the ring channel at a side of the channel in proximity to the impeller. Ring channel blowers of standard construction operate relatively noisily, which is increasingly felt to be inconvenient when, corresponding to current efforts by motor vehicle producers, the passenger compartment is becoming less noisy due to soundproofing. In particular, with the use of such ring channel blowers in a motor vehicle heater, the operation of the heater can be perceived in the passenger compartment of the motor vehicle.